http://arxiv.org/abs/2301.02866
We performed a study of high redshift ($z>2$) quasars, looking for the main differences between Radio Loud Quasars (RLQ) and Radio Quiet Quasars (RQQ) in the X-ray band. Our sample of 472 RQQ and 81 RLQ was selected by cross-matching the SDSS DR7 quasars catalog with the Chandra Source Catalog. We computed the X-ray luminosity for the two samples and confirmed the X-ray luminosity excess of RLQ over RQQ. We fit the X-ray spectra assuming the absorbed power law model and obtained the photon index ($\Gamma$) values for all the sources in the sample. We excluded quasars with a low number of counts ($<10$) and large uncertainty on the best-fit photon index ($\Gamma_{err}>1$), and obtained the mean values of $\Gamma_{RLQ}=1.70 \hspace{0.5mm}{-0.33}^{+0.36}$ and $\Gamma{RQQ}=2.19 \hspace{0.5mm}{-0.44}^{+0.46}$ for the RLQ and RQQ samples, respectively, showing that the RLQ have flatter (harder) X-ray spectra than RQQ. The Kuiper-two test confirms this result with the significant difference between the RLQ and RQQ photon index distributions ($D{k}=0.37$ and P-value $= 10^{-6}$). We also evaluated the hardness ratio distributions and confirmed that the spectra of RLQ are flatter than the spectra of the RQQ. The RLQ’s hard-to-soft ratio distribution is skewed towards the hard X-ray band, while the RQQ is towards the soft X-ray band. The hard-to-medium and medium-to-soft ratios show no difference.
F. Shaban, A. Siemiginowska, R. Suleiman, et. al.
Tue, 10 Jan 23
92/93
Comments: N/A